FEETILTZATION IN PLANTS. 
425 
evidence in the direction in which scientific thought has drifted 
during the past few years to deny that Darwinism/^ as it has 
been termed^ has modified and is continuing to modify opinions 
on all subjects within its scope. Let it not be supposed that 
because we have admitted so much, because we dare not refuse 
to recognize this fact, that we are therefore prepared to swear by 
the book, the whole book, and nothing but the book, or that 
it is our purpose to champion its author, and vindicate its cause. 
There are two phases in which we think that Mr. Darwin is to 
be regarded — as the advocate of a theory, and as a practical 
worker — it is the latter phase more particularly which concerns 
us on the present occasion ; and that, too, with more especial 
reference to vegetable forms and functions. 
Three years ago, appeared his work on the fertilization of 
Orchids,* and since then other shorter contributions to Botani- 
cal Science. These will serve as the texts for our brief com- 
mentary. To understand the direction of his observations, 
and the deductions therefrom, it will be necessary to indicate 
the peculiarities of structure in the plants subjected to experi- 
ment. These are amongst the most singular and attractive in 
the vegetable world, not only on account of the extraordinary 
forms which their fiowers assume, but for the structure of their 
reproductive organs. In ordinary plants the centre of the 
flower is occupied by the pistil, the lower portion of which 
encloses the ovary, and contains the ovules, which, after ferti- 
lization, swell, mature, and become seeds; the ovary is sur- 
mounted by a cellular elongated filament, called the style 
(occasionally absent). The upper extremity of the style is 
clubbed or divided, and bears a viscid surface, known as the 
stigma. All these parts together constitute the pistil. Ar- 
ranged about this organ stand a series of more or less slender 
erect threads ; there may be three, or five, or twenty, according 
to the plant which produces them. Each of these threads or 
filaments bears on its summit an elongated yellowish or 
brownish sac or vesicle, termed the anther, enclosing a yellow 
powder, which, when ripe, ruptures the vesicle or anther, and 
is dispersed ; this is the pollen. The whole organ is a stamen. 
When the pollen is shed from the anthers, some of the granules 
adhere to the sticky surface of the stigma; a kind of germination 
takes place ; long slender tubes emanate from some portion 
of the surface of the pollen grains, pass downwards through 
the cellular style into the ovary, enter the ovules at the base or 
point of attachment of the ovules to the walls of the ovary or 
its central axis, the fluid contents of the pollen grain then pass 
^ “On the Various Contriyances by which British and Foreign Orchids 
are fertilized by Insects.” — London : Murray. 1862. 
